1. Field of the Invention
The present invention generally relates to an optical fiber holder which can securely and orderly holds the connection portions of optical fibers.
Various types of communication and processing and transmission of information signals are carried out by virtue of light as a transmission medium that can cope with large volumes of signal transmission. Optical fibers, which are suitable for large-volume, long-distance transmission of multiplexed optical signals, are being widely used today. Various apparatuses can be used as signal processing apparatuses and transmission/reception apparatuses. Such apparatuses are placed in desired positions both indoors and outdoors. Although each apparatus is internally made to have high density, there are a number of restrictions on installing optical fibers inside the apparatus.
In each apparatus, it is necessary to connect optical fibers between components. Accordingly, optical connectors for detachable connection, and welding for permanent connection hereinafter referred to simply as xe2x80x9csplice connectionxe2x80x9d or xe2x80x9cconnection portionxe2x80x9d) can be applied in connecting optical fibers.
An optical connector can easily connect and separate optical fibers to and from each other. However, attaching optical connectors to an apparatus requires a long period of time and special equipment as well as skill. Moreover, attaching and detaching optical fibers to and from optical connectors, and the optical connectors themselves take up a large space in the apparatus.
Though non-detachable, splice connection has the following advantages: short operation time; little transmission loss and high reliability; and small space required for directly connecting optical fibers. A splice connection can be made by connecting the end faces of a pair of optical fibers facing each other, or by connecting a plurality of optical fibers. Such a splice connection can be applied in gathering optical signals from optical fibers and dispersing optical signals into optical fibers, where necessary.
2. Description of the Related Art
FIG. 1A is a perspective view of an example of the connection portion of optical fibers. The connection portion 1 is made by welding the end faces of a pair of single-core optical fibers 2 facing each other. The coating on the end faces of the optical fibers 2 is removed, and the centers of the two optical fiber wires are precisely matched with each other, and are welded by arc discharge heat. The connected parts of the wires are coated with a synthetic resin (not shown), and are thus shielded. FIG. 1B is a sectional view of the connection portion 1 of FIG. 1A. A metal line 3 made from stainless steel for strengthening the connection portion 1 extends in the longitudinal direction, and the entire connection portion 1 is covered with a coating 5 for protection. Although not shown in the figures, the optical fibers 2 actually extend over great distances from both ends of the connection portion 1.
The optical fibers 2 cannot be installed as they are shown in the figures in the apparatus, because the weight of the connection portion 1 is applied as a load onto the optical fibers 2. Therefore, it is necessary to employ a holding unit to support the connection portion 1. Furthermore, since a number of connection portions of optical fibers often exist in an apparatus, each holding unit needs to have special means to avoid confusion.
FIG. 2 is an exploded view of a conventional holding unit developed in response to the above demand. In an apparatus, screw holes 12 for attachment are formed in the surface of the printed board 11 of a printed board unit, and a plurality of connection portions 1 of optical fibers are arranged in parallel. A presser plate having a width corresponding to the total width of the connection portions 1 is placed on the aligned connection portions 1 and is screwed to the printed board 11 with screws 16. The presser plate 15 is a conventional optical fiber holder.
FIG. 3 is a front view of the conventional optical fiber holder screwed to the printed board. The connection portions 1 are orderly aligned and tightly held, as shown in the figure. The optical fiber holder 15 may be made of a given synthetic resin or metal, and is preferably made of an aluminum alloy plate or a stainless steel plate for ease of formation depending on the total width of the connection portions 1.
Since the shape of the section of each connection portion 1 is elliptical or oval as shown in FIG. 1B, it is necessary to shift the connection portions 1 when the optical fiber holder 15 is placed over them. If each of the connection portions 1 is pushed in the direction of the wider diameter, the connection portions 1 are automatically rotated so that they are pushed in the direction of the narrower diameter. In such a case, twists are caused to the optical fibers 2. If the optical fibers 2 do not have enough extra lengths to allow such twists, twisting stresses are internally caused, thereby reducing the optical transmission rate of the optical fibers.
Also, if some of the connection portions 1 are pressed in the direction of the wider diameter while the other are pressed in the direction of the narrower diameter, those pressed in the direction of the wider diameter can be secured, but those pressed in the direction of the narrower diameter each leave a gap from the optical fiber holder 15. As a result, the connection portions 1 pressed in the direction of the narrower diameter are insecure and might slip off the optical fiber holder 15. In order to avoid this, it is necessary to take the trouble to position the connection portions 1 of the optical fibers 2 all in the same direction.
In a case where the number of connection portions 1 increases beyond the capacity of an area reserved for disposing the connection portions 1, it is necessary to keep another area as shown in FIG. 4. In view of the density of the entire apparatus, however, it is difficult to keep a reasonably large area as shown in FIG. 4. The connection portions 1 are inevitably dispersed, or the structure of the apparatus is made more complicated so as to create a large area for disposing the connection portions 1. Furthermore, a connection portion disposing area cannot be set anywhere, but it has to be situated on or in the vicinity of the paths of the optical fibers. It also has to be situated in a place where connecting and disconnecting operations can easily be carried out.
It is a general object of the present invention is to provide an optical fiber holder in which the above disadvantages are eliminated.
A more specific object of the present invention is to provide an optical fiber holder which accommodates coated connection portions of optical fibers orderly arranged side by side at predetermined intervals while maintaining high density.
The above objects of the present invention are achieved by an optical fiber holder comprising: a holder body including an optical fiber accommodating unit having recess portions defined by first protrusions arranged side by side, coated connection portions of optical fibers being respectively accommodated in the recess portions; and a presser member attached to the holder body, the presser member having second protrusions corresponding to the first protrusions and covering the coated connection portions of the optical fibers.
Since the connection portions of optical fibers are respectively inserted in the separate recess portions of the optical fiber accommodating unit, the connection portions can be accurately positioned in a desired state. Also, the presser member covering the connection portions further stabilizes the connection portions in the separate recess portions.
The above objects of the present invention are also achieved by an optical fiber holder comprising a holder body which includes: an optical fiber accommodating unit having recess portions defined by first protrusions arranged side by side, coated connection portions of optical fibers being respectively accommodated in the recess portions; and second protrusions formed on the rear surface of the optical fiber accommodating unit, the second protrusions corresponding to the first protrusions.
With this structure, a plurality of holder body can be laminated on one another to accommodate a large number of connection portions of optical fibers. In such a case, the bottom surface of an upper one of the holder bodies presses on the connection portions accommodated by a lower one of the holder bodies. The recess portions of the lower holder body are completely partitioned by the protrusions formed on the rear surface of the optical fiber accommodating unit of the upper holder body, thereby further stabilizing the connecting portions accommodated in the lower holder body.
The above objects of the present invention are also achieved by an optical fiber holder comprising a holder body which includes: an optical fiber accommodating unit having recess portions defined by first protrusions arranged side by side, coated connection portions of optical fibers being respectively accommodated in the recess portions; and a plurality of attachment holes are respectively formed on both sides of the optical fiber accommodating unit, said plurality of attachment holes include screw holes and screw insertion through holes.
If a plurality of holder bodies are laminated on one another, the lowermost holder body is attached to the attachment surface by screws, while the holder body directly above the lowermost holder body can be attached to the lowermost holder body by putting the screws into the screw holes of the lowermost holder body. Thus, the lengths of all the screws can be made uniform.
The above objects of the present invention are also achieved by an optical fiber holder comprising a holder body including optical fiber guide notches formed at uniform intervals in side walls facing each other, and an optical fiber accommodating unit having an inner flat surface which is an adhesive surface for positioning coated connecting portions of optical fibers accommodated in the optical fiber accommodating unit; and a presser member attached to the holder body, the presser member covering the optical fiber accommodating unit.
With this structure, the connection portions of optical fibers can be orderly positioned by the optical fiber guide notches formed on both sides of the optical fiber accommodating unit, and the connection portions are also stabilized by the adhesive surface in the optical fiber accommodating unit. Thus, the connection portions of optical fibers can be stabilized in a desired state.
The above objects of the present invention are also achieved by an optical fiber holder comprising a holder body which includes: an optical fiber guide notches formed at uniform intervals in side walls facing each other; an optical fiber accommodating unit having an inner flat surface which is an adhesive surface for positioning coated connection portions of optical fibers accommodated therein; and a plurality of attachment holes formed on both sides of the optical fiber accommodating unit, the plurality of attachment holes including screw holes and screw insertion through holes.
If a plurality of holder bodies are laminated on one another, the lowermost holder body is attached to the attachment surface by screws, while the holder body directly above the lowermost holder body can be attached to the lowermost holder body by putting the screws into the screw holes of the lowermost holder body. Thus, the lengths of all the screws can be made uniform.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.